In the past it has been common practice to use various types of hard and rigid metal or plastic materials to fabricate shields or guards which can be used to protect an individual during sporting events or other types of strenuous activity. In many cases, a hard and rigid shell which fits the overall general contour of that part of the body which is intended to be protected is combined in conjunction with a pad, usually of a soft cloth or foam material, which cushions the shell from contact with the user's body. Thus, an impact or blow to this protected part of the body allows the impact or energy of the blow to be distributed over a broader area allowing the body to absorb the energy without injury or damage.
One of the biggest problems with the conventional guards or shields which have been used in the past is the fact that these shields do not generally fit the specific part of the body that is intended to be protected. Most shields are sized and shaped to fit the average person and as we well know there is no average person. Every individual is different and it is common knowledge that there is a difference between even the legs, arms and other areas of some individuals. As a result, the shields that have been used to date have been found to be inadequate and fail to fully protect the user's body. This is to say that even though they have performed an adequate function up to this point the present guards or shields still allow a number of injuries, primarily because the guards or shields do not properly fit the user and thus do not properly couple and dissipate the impact energy that is applied to the guard.
In the past, various types of moldable materials have been used to mold an individual product to the individual user. This type of approach to the problem has been primarily applied in mouth guards which are used for many athletic events and also for orthopedic appliances, such as splints and braces.
With respect to the orthopedic devices, usually a foam pad is applied to the underside of the splint in order to render the device more comfortable when the device is used for a long term without removal. In many cases with orthopedic devices the material that is used is quite rigid to prevent any flexure or movement in the body part or joint over which the splint is applied. Thus, the materials that have been used dictate the methods of applying temperature in order to soften the material so that it can be formed. One of these materials is "Plexiglass" which requires a temperature of approximately 149.degree. C. (300.degree. F.) in order to allow the material to be pliable enough to be formed. Naturally a temperature of this magnitude is quite difficult to handle and is unsafe when heated. This material presents problems in applying the heat as well as possibly burning or injuring the patient when the device is shaped.
The plastic mouth guard products which have been in use for a number of years have been fabricated from materials which are far softer and more pliable then those used in pads, shields or guards used to protect participants in sport contests. As a result of the pliability of the particular materials used and the fact that the material is used in the mouth, the problems which exist in the manufacture and use of the mouth piece guard are quite different than those encountered in body guard products. It is acknowledged that the material used in a mouth protector is of the mid-temperature type which can be softened and molded by immersion in boiling water. One of the major differences is that the mouth protector is used within the body and thus is maintained at a relatively constant body temperature of approximately 38.degree. C. (98.degree.-100.degree. F.). As a result, the material must set and retain its shape at higher temperatures than those required for normal ambient temperature use. In addition, the material that is used must have stringent specification requirements which relate to body compatibility.
The problems encountered with these products are considerably different than those which are encountered in the attempt to shape or fit an external guard or shield to the outside surface of the user's body in order to more completely protect the user from injury.